For many decades now, the mysteries of our quantum underworld have at times been confused with the other conundrum that confronts us, the nature of consciousness. But in “Helgoland,” the theoretical physicist Carlo Rovelli tackles both the quantum realm and the ways it helps us make sense of the mind with refreshing clarity and without hand-wavy mystery-mongering.
The book’s title refers to an island in the North Sea, where a 23-year-old German physicist named Werner Heisenberg had an epiphany. In 1925, Heisenberg had decamped to the treeless island to alleviate his allergies. Amid its wind-swept desolation, Heisenberg would have insights that formed the basis of modern quantum theory.
The conceptual breakthrough initiated by Heisenberg (who was mentored by Niels Bohr), and firmed up with contributions from Max Born, Wolfgang Pauli, Paul Dirac, Erwin Schrödinger and others, makes it clear that the world of the very small — that of photons, electrons, atoms and molecules — obeys rules that go against the grain of our everyday physical reality.
Take an electron that is emitted at Point A and is detected at Point B. One would assume that the electron follows a trajectory, the way a baseball does from a pitcher’s hand to a catcher’s mitt. To explain experimental observations, Heisenberg rejected the notion of a trajectory for the electron. The resulting quantum theory deals in probabilities. It lets you calculate the probability of finding the electron at Point B. It says nothing of the path the electron takes. In its most austere form, quantum theory even denies any reality to the electron until it is detected (leading some to posit that a conscious observer somehow creates reality).